The large-scale crossbar array is a promising architecture for hardware-amenable energy efficient three-dimensional memory and neuromorphic computing systems. While accessing a memory cell with negligible sneak currents remains a fundamental issue in the crossbar array architecture, up-to-date memory cells for large-scale crossbar arrays suffer from process and device integration (one selector one resistor) or destructive read operation (complementary resistive switching). Here, we introduce a self-selective memory cell based on hexagonal boron nitride and graphene in a vertical heterostructure. Combining non-volatile and volatile memory operations in the two hexagonal boron nitride layers, we demonstrate a self-selectivity of 10 10 with an on/off resistance ratio larger than 10 3 . The graphene layer efficiently blocks the diffusion of volatile silver filaments to integrate the volatile and non-volatile kinetics in a novel way. Our self-selective memory minimizes sneak currents on large-scale memory operation, thereby achieving a practical readout margin for terabit-scale and energy-efficient memory integration.

Vertically stacked two-dimensional van der Waals (vdW) heterostructures, used to obtain homogeneity and band steepness at interfaces, exhibit promising performance for band-to-band tunneling (BTBT) devices. Esaki tunnel diodes based on vdW heterostructures, however, yield poor current density and peak-to-valley ratio, inferior to those of three-dimensional materials. Here, we report the negative differential resistance (NDR) behavior in a WSe2/SnSe2 heterostructure system at room temperature and demonstrate that heterointerface control is one of the keys to achieving high device performance by constructing WSe2/SnSe2 heterostructures in inert gas environments. While devices fabricated in ambient conditions show poor device performance due to the observed oxidation layer at the interface, devices fabricated in inert gas exhibit extremely high peak current density up to 1460 mA/mm2, 3–4 orders of magnitude higher than reported vdW heterostructure-based tunnel diodes, with a peak-to-valley ratio of more than 4 at room temperature. Besides, Pd/WSe2 contact in our device possesses a much higher Schottky barrier than previously reported Cr/WSe2 contact in the WSe2/SnSe2 device, which suppresses the thermionic emission current to less than the BTBT current level, enabling the observation of NDR at room temperature. Diode behavior can be further modulated by controlling the electrostatic doping and the tunneling barrier as well.

Bonding geometry engineering of metal–oxygen octahedra is a facile way of tailoring various functional properties of transition metal oxides. Several approaches, including epitaxial strain, thickness, and stoichiometry control, have been proposed to efficiently tune the rotation and tilt of the octahedra, but these approaches are inevitably accompanied by unnecessary structural modifications such as changes in thin‐film lattice parameters. In this study, a method to selectively engineer the octahedral bonding geometries is proposed, while maintaining other parameters that might implicitly influence the functional properties. A concept of octahedral tilt propagation engineering is developed using atomically designed SrRuO 3 /SrTiO 3 (SRO/STO) superlattices. In particular, the propagation of RuO 6 octahedral tilt within the SRO layers having identical thicknesses is systematically controlled by varying the thickness of adjacent STO layers. This leads to a substantial modification in the electromagnetic properties of the SRO layer, significantly enhancing the magnetic moment of Ru. This approach provides a method to selectively manipulate the bonding geometry of strongly correlated oxides, thereby enabling a better understanding and greater controllability of their functional properties.

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Growth of 2D van der Waals layered single‐crystal (SC) films is highly desired not only to manifest the intrinsic physical and chemical properties of materials, but also to enable the development of unprecedented devices for industrial applications. While wafer‐scale SC hexagonal boron nitride film has been successfully grown, an ideal growth platform for diatomic transition metal dichalcogenide (TMdC) films has not been established to date. Here, the SC growth of TMdC monolayers on a centimeter scale via the atomic sawtooth gold surface as a universal growth template is reported. The atomic tooth‐gullet surface is constructed by the one‐step solidification of liquid gold, evidenced by transmission electron microscopy. The anisotropic adsorption energy of the TMdC cluster, confirmed by density‐functional calculations, prevails at the periodic atomic‐step edge to yield unidirectional epitaxial growth of triangular TMdC grains, eventually forming the SC film, regardless of the Miller indices. Growth using the atomic sawtooth gold surface as a universal growth template is demonstrated for several TMdC monolayer films, including WS2, WSe2, MoS2, the MoSe2/WSe2 heterostructure, and W1−xMoxS2 alloys. This strategy provides a general avenue for the SC growth of diatomic van der Waals heterostructures on a wafer scale, to further facilitate the applications of TMdCs in post‐silicon technology.

An effective approach to alleviate the volume expansion of alloying material and magnify the capacity of sodium-ions batteries anode by anchoring the SnS nanoparticles densely on porous carbon nanotubes film.

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Electrides have emerged as promising materials with exotic properties, such as extraordinary electron-donating ability. However, the inevitable instability of electrides, which is caused by inherent excess electrons, has hampered their widespread applications. We report that a self-passivated dihafnium sulfide electride ([Hf2S]2+∙2e−) by double amorphous layers exhibits a strong oxidation resistance in water and acid solutions, enabling a persistent electrocatalytic hydrogen evolution reaction. The naturally formed amorphous Hf2S layer on the cleaved [Hf2S]2+∙2e− surface reacts with oxygen to form an outermost amorphous HfO2 layer with ~10-nm thickness, passivating the [Hf2S]2+∙2e− electride. The excess electrons in the [Hf2S]2+∙2e− electride are transferred through the thin HfO2 passivation layer to water molecules under applied electric fields, demonstrating the first electrocatalytic reaction with excellent long-term sustainability and no degradation in performance. This self-passivation mechanism in reactive conditions can advance the development of stable electrides for energy-efficient applications.